Water-resistant sandpaper and other abrasive papers and process of making same



llatented reuia'iaae I g R 2,031,362

UNITED STATES PATENT OFFICE" WATER RESISTANT SANDPAPER AND OTHER ABRASWE PAPERS AND PROCESS OF MAKING Carleton Ellis, Montclair, N. 3., minor to Ellis- Foster Company, a corporation or New Jersey No Drawing. Application February 18, 1927, Serial No. 169,412. Renewed September 9, 1933 9 Claims. ci. 51-280) This invention relates to water-resistant abranot preclude the employment or natural resins, sive papers or cloths such as sandpaper or emery preferably in conjunction with the synthetic cloth, abrasive strips for dental purposes. and products specified. Neither does it preclude the relates e pecially tov such abrasive sheets conemployment of natural resins which have been taining a. binder of nitrocellulose and certain modified by chemical treatment, as for example, 5

resinous bodies, as will be morefully hereinafter specially oxidized resins, or those which have described. The present method of producing been treated with gly rol. lycol, and the lik water-resistant sandpaper involves the employo make esterifled Products ester 8 ment of what is known as along oil varnish. The A type of resin which I find adapted for the 0 use of this material requiresprotracted baking purpose is that made by reacting on glycerol 10 in order to bring about drying. Furthermore, with one or more resinifying organic acids. when such abrasive paper is kept in storage for Thus, products such as benzoic salicylic glyca year or more, oxidation of the binder progresses eride resin, benz ph li rid r in. caswith consequent brittleness and deterioration. tor oil phthalic glyc'eride resin, may be employed.

iii In the present invention a binder of a less A suitable resin is that obtained by heating :5

readily oxidizable nature, or' one which is even substantially free from progressive. oxidation 1 l v Parts y W ng; p ly is employed. Furthermore, a binder fi and 80 is utilized which does not demand theprotracted P c a 45 2o rying and seasoning period of the long oil varmstlued'cottonseed y M Wish Process. the temperature being carried to about 240 C. The form of nitrocellulose which I may emp y until a product of an acid number of say, twenty, is a. high viscosity nitrocellulose such as the sois t d a d lluloid tt r I ay employ h low A modified form of resin is obtaizied by treato ty nit u of say, One-half Second ing the foregoing in solution with one or two per viscosity, or slightly higher viscosity such as. t of its weight of sulphur monochlorlde. A tour second nitrated cotton. 'Various forms of nquid product may be obtained by heating gelatinized nitrocellulose such as waste or scrap.

celluloid, worn-out moving picture film freed Ports byweight to from emulsion, smokeless powder t p d y l 200 the like, may be employed in som a e h Cottonseed fatty acids 56t viscosity nitrocellulose such as celluloid tt 7 Phthalie anhydride 296 oi about twenty-five second viscosity (reckoned the temperatur being raised gradually m 0 Q in terms of lacquer viscosity measurement) has This liquid product is useful as a sofmmng' and relative highstrength, toughness and flexibility, plasticizing Substance for nitrocellulose and 35 but being of high viscosity a greater proportion parts good binding and adhesive qualities. of solvent is required in Preparing solution of The nitrocellulose therefore afiords strength g fim i g? 2 the am :2 g and toughness and the resinous body, or the liqng on e presen ven on. e ow scos y 40 nitrocellulose such as the one-half second type um synthetic products of type such 85 that last 40 described, promote binding action and adhesion,

serving to retain the particles of grit to an advantageous degree when the sandpaper is putetci use.

A composition was prepared as fo1lows:-

Parts by weight 41 does not call for as much solvent, but on the other hand the coating is not as strong and .permanent as that obtained with the high viscosity product. A four second to ten second nii't troceliulose possesses intermediate properties. In

some cases a mixture of high viscosity and low (a) One-half second nitrocellui se 4o viscosity nitrocellulose may be utilized. Acetone 100 As stated above I preferably employ a resinous Tricresyl phosphate 80 substance in conjunction with the nitrocellulose.

Preferably such resinous material is prepared by (b) Cottonseed phthalic glyceride Team}! the 50 synthesis in order to get a more-compatible prodtype first described was dissolved in on qual uct as most' of the natural resins are not as weightof a mix r f 4 D 11 11 1 p -capable of blending and assimulating with nitromonochlorbenzol.

cellulose as some of the synthetic products which 20 parts by volume of solutions (a) and (b) will be described. The foregoing, however, does were mixed, 5 parts of hutyl acetate and 5 parts 56 with water.

of a plasticizing agent composed of equal parts of tricresyl phosphate and castor oil were added.

A coating of this composition was applied to strong well-sized kraft paper and before the coating had time to dry emery powder or fine sand was dusted on the surface. On drying for a few minutes in a warm oven the abrasive paper was ready for use.

Another binding composition was made from Parts Nitrocellulose; 8 Cottonseed phthalic glyceride resin B Tricresyl phosphate 12 Secondary amyl acetate 20 Secondary butyl alcohol 10 Ethyl acetate 10 Benzol i 20 This solution was applied to a paper backing and before drying occurred carborundum grit was sprinkled on the surface and the coating dried a few minutes in a warm oven. The opposite side of the sheet was coated with the same composition without the grit. A flexible abrasive paper was obtained to which the abrasive was quite" same, which discloses and claims the production of water-resistant paper by the use of wax dispersions; 106,575, filed December 31, 1928, entitled Container and hood cap therefor, Patent No. 1,739,581, which discloses and claims closures particularly for bottles, which closures are made from paper carrying substances such as wax, etc., acting as dye lubricants in the drawing of such paper containers; and Serial No. 107,461 filed November 15, 1928, entitled Water-resistant paper disc stopper for milk bottles and the like, Patent No. 1,739,582, disclosing and claiming closure's for containers, and particularly disc types of stoppers, made from pulp carrying wax emulsions, etc. and'United States Patents 1,607,517; 1,607,518; 1,607,519 and 1,607,552. I

In the preferred form of the present invention it is an object to produce a. water resistant abrasive sheet in order that the product may be employed to rub down surfaces which are moistened The employment of water resistant paper as asuppor'ting material and the use of nitrocellulose and resin as aforesaid affords an abrasive sheet having the requisite qualities.

The proportion of nitrocellulose to resin given in the illustrative formulas is not one which should be rigidly followed in all cases. The size and kind of grit employed and the purpose for which the abrasive sheet is to be used will govern to a considerable extent the ratio between nitrocellulose and resin. In somexzases the resin may be present in minor proportion, while in other cases it should be present in major proportion. The resins specified represent a type particularly useful for the purpose because they may be employed in major proportion, that is, say, to one part of nitrocellulose two to eight parts of resin quirements in hand. When soft resins are usedin considerable proportion less plasticizer will be required. When using a synthetic liquid product prepared as described above plasticizer may be omitted entirely if such liquid body is employed in substantial proportion.

Retardation of drying of the solvent from the coating may be accomplished by the. addition of a small amount of a mineral wax, beeswax, or

some vegetable waxes, one or two per cent of the wax usually being sufficient.

In some cases the .abrasive may be lightly coated with the solution of binder by suitable pre-mixing and the mass rolled out onto a sheet of supporting material.

Abrasive sheets for other purposes such as the narrow strips employed by dentists for cleaning and polishing teeth may be made in like manner. For example, tracing cloth may be coated with a nitrocellulose composition as. above and the surface, while still moist, dusted with fine pumice, cuttlefish powder, and the like. Similarly the paper discs employed by dentists for cleaning and polishing purposes may be coated with suitable abrasive material held in place by the binding agent aforesaid.

To minimize flre hazard, triphenyl or tricresyl phosphate may be employed as plasticizing agents and ground gypsum, perhydrated calcium sulphate or magnesium carbonate may be incorporated in the coating as fire retarding agents. Abrasive papers are obtainable, using a nitrocellulose binder, which areless easily ignited than papersproduced with the aid of a long oil varnish.

What I claim is:-

1. An abrasive sheet comprising paper rendered water-resistant by wax deposited from emulsion in the paper stock, said water-resistant paper carrying a coating of abrasive grit bound to the surface by a binder comprising a nitrocellulose composition.

2. An abrasive sheet comprising paper rendered water resistant by wax deposited from emulsion in the paper stock, said water resistant paper carrying a coating of abrasive grit bound to the surface by a binder.

3. An abrasive sheet comprising paper rendered water resistant by wax deposited from emulsion in the paper stock, said water resistant paper carrying a coating of abrasive grit bound to the surface by a binder containing a synthetic resin.

4. An abrasive sheet comprising a water resistant paper support carrying a coating of finely divided grit bound to the surface of the paper by nitrocellulose and a synthetic resin of the glyceride type.

5. An abrasive sheet comprising water-resistant paper carrying a coating of a finely-divided abrasive grit bound to the surface by a binder comprising nitrocellulose and cottonseed oil phthalic glyceride resin.

6. An abrasive sheet comprising water-resistant waxed paper carrying a coating of a finelydivided abrasive grit bound to the surface by a binder comprising nitrocellulose and cotton seed oil phthalic glyceride resin.

'7. An abrasive sheet material comprising a base, abrasive material and. a coating on said base comprised of an oil-modified polyhydric alcohol-polybasic acid resin and nitrocellulose.

8; An-abrasive sheet material comprising a waterresistant base, abrasive material and a coating'on said base comprised of an oil-modifled polyhydric alcohol-polybasic acid resin and nitrocellulose.

9. An abrasive sheet comprising a water-resistant paper support carrying a coating of finely divided grit bound to the surface of the paper by a composition containing a cellulose ester and a synthetic resin of the glyceride type, said paper support carrying a backing of a composition containing cellulose ester and a synthetic resin of the glyceride type in order to waterproof the same. 

